Process of preparing a monobasic salt of a secondary amine



Patented Apr. 7, 1953 noonss or PREPARING A moNoeasro SALT or a snooNnARY AMINE Lu as: J- Kr id s Zreh a liich nd Fer nand B. Z'enty, St. Louis, Mo., assignors to Monsanto ihhq l aware,

N Drawing.

at m any ent M94 ns e:-

Original application October 4,

1946, Serial No. 701,078. Divided and this ape plication November 26, 1947, Serial No. 788,318

5 Qlaims 1;

Th s i ven ion relat t a no el improvement n the hr na a iqh t e tia y a ne nd m e partishla r to t ia entries r h m l Ba nl-r t onzo-mmoam n hich it; s a. radica er ated fr m he. oup.

n s ng o anti-me h l and. h l-msthyl i an B2: i a. etinal elett om h group cohfiisting of; aryl, allgyl', 'cyoloalhyl, aryle n h ylh hy radic l On tin a s con ar amine f he qrm re a inwhioh Rrepresents a radical of the type hereinbefore described as R1 or R: with a compound of the type RX'X in which 13,? is a radical of the type defined hereinabove as R1, and X is chlorine h omiha lar mount f uaterna sa ete'ie rimecl re h s ah a none Qt h e ired erti ry was fo m d- The se Of low em r tur a d t solut id n t avoid rm on Q la g amou t of q at r ry l When e nda y mi is one having the ormula 2 ctors?- h pr lem us descri ed appears to he h a h or h s wh arr amine i h h 1 N s h i ue s a e methy radi s- M r o e when the dihyd ochloride orother d v-sa O a secondary w in h ing th fhrmhlai RF-N'C-HIQHZ'N,

in which its and R4 are alkyl groups, is heated with the halide of the formula Rf-X substantially none of the desired tertiary amine is formed.

According to the present invention, ge

in which 13, represents a, radical selected from the group consisting of It; and R2, R1 beingdefined as a group of radioals consisting of aryl-methyl and thie-nyl methyl radicals and R2 being defined as agroup of radicals consisting of aryl, alkyl,

ane.- W h n. eahit h i of t tormh a in hi h Rf' s Q h r d ca s R1. and s i br mine or qhl r he Th mi hte s rare o am l a nt th re ti n t: ult g n the orm ti n o h d s ed, tertiary ami e s c eted r xa p n a a entme als 4 a 6 o r h e tia r' am e s reco e d x m le a a al f om he te th m x r y a d ir rq hr or e am e by rendering h r att ph m xture k ine wit td hmh rox de ol t on tqveri s the ase. whi h s par es s ol ng the. amih he n an solyeht 1th a e h r- Q: a mixt 9?? hot etra h oride and a e tne an tr ati he s lt i n. hus ormed. w th dr dr e them as a ount uffi eht Q term the mqhqhv heh h 0. ihydre h pride at he, t ar a: e he er iary m ne alt ma h .v rified, t0.

ine prr ximatel We q W t r-1 Any desired method of preparlng the mano aste alt f. the. sechnd ry amine hereihahh e described he ample-Yet r0 startle; he monohydrochloride can be prepared by treating a benzene solution of the said secondary amine with a benzene solution of hydrogen chloride in amount sumcient to form themonohydrqohloride of the secondary amine. Another method oi preparingthe monohydrochloride is to heat one mole of the secondary amine in an organic solvent such as benzene, acetone, or alcohol, with one mole of an ammonium salt of a mineral acid such as ammonium chloride, ammonium bromide, ammonium sulfate, or ammonium nitrate, and a small quantity of water until evolution'of ammonia ceases. The monobasic salt of the secondary' amine may be utilized in the solvent medium in which it is prepared for the purpose of preparing the tertiary amines of the present inven- 7 vents if desired. Similarly, the acid sulfate of the secondary amine can be prepared from one mole 'of the secondary amine and mole of ammonium sulfate. A further method or preparing he mono-hydrochloride is to treat one mole ot the tttohdartf tthihe With ne m e Q eeters h drochloric acid followed by evaporatin to dry,- ness.- Other salts, such as the monohydrobromide, monobasic phosphate, monobasic nitrate, or monobasic salt of any of the mineral acids, can be prepared by the above procedures as well as by other methods known to those skilled in the art.

Suitable aryl-methyl radicals for the purpose of the present invention may include, for example, the benzyl radical, substituted benzyl radicals such as para-isopropyl-benzyl (cumenyl), dimethoxy-benzyl (veratryl) and para-chlorobenzyl radicals. Suitable thienyl-methyl radicals for the purpose of the present invention are the thenyl radical and substituted thenyl radicals such as the -chloro-thenyl, 5-bromo-thenyl, and 5-methyl-thenyl radicals and other substituted thenyl radicals containing methyl groups substituted in the 4 and 5 positions of the thiophene residue.

Suitable radicals for the R2 position in the preparation by the method of the present invention of the tertiary amines hereinbefore described are the phenyl radical, substituted phenyl radicals such as the chlorophenyl radicals, the toluene radical, the xylenyl radical, and the alkoxyphenyl radical; alkyl radicals such as the methyl, ethyl, propyl, isopropyl, and butyl radicals; cycloalkyl radicals such as the cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl radicals; the biphenyl radical, substituted biphenyl radicals, the alpha or betanaphthyl radicals, the alpha or beta methyl naphthyl radicals, the benzyl radical and substituted benzyl radicals such as the cumenyl and para-chlorobenzyl radicals.

Suitable organic solvents for use in the process of the present invention are benzene, toluene, xylene, petroleum ether, dioxane, acetone,- alcohol, methanol, and butanol. The equivalent ratio of monobasic salt of the secondary amine to organic halide may range from 1:1 to 4:1 or even higher. The temperature of the reaction is not particularly critical and may range, for example, from 0 C. or lower, to -110 C. or even higher, depending upon the conditions selected for the reaction.

The following examples will serve to illustrate the novel process of the present invention:

Example I To a solution of 26.6 grams (0.162 mole) of N- phenyl-N-N'-dimethyl-ethylenediamine in 100 cc. of benzene were added 8.7 grams (0.162 mole) of ammonium chloride and 0.5 cc. of water. The mixture was refluxed for 10 hours during which time ammonia was evolved. The resulting mixture was cooled to C.. a solution of 10.7 grams (0.181 mole) of 2-thenyl chloride in cc. benzene was added and the resulting mixture was heated at 65-70 C. for 5 hours. Thereafter, grams of sodium hydroxide solution and 40 cc. of water was added. The mixture was stirred vigorously at -60 C. for 1 hour. The benzene layer was then separated and distilled. There was recovered 7.0 grams of N-phenyl-N- (2 thenyl) -N,N' dimethyl-ethylenediamine in the form of a yellow oil, boiling point 185-188 C./8 mm. The oil was dissolved in a 3 to 1 mixture of carbon tetrachloride and acetone. To the solution was added sufficient dry hydrogen chloride toform the monohydrochloride of the tertiary amine. On recrystallization from acetone containing 4% water, the monohydrochloride melted at 183-184 C. (corrected).

In the procedure of the present example, the monohydrochloride of N-phenyl-N,N'-dimethyl ethylenediamine may be recovered, if desired from.

Example II The procedure described in Example I was repeated, using 0.162 mole of N-phenyl-N',N'-diethyl-ethylenediamine and 0.162 mole of Z-thenyl chloride. Excellent yields of N-phenyl-N-(Z- thenyl)-N',N'-diethyl-ethylenediamine were obtained.

Example III To a solution of 16.4 grams (0.10 mole) of the free base, N-phenyl-YZN-dimethyl-ethylenediamine, in 25 cc. of butanol held at 4550 C., there was slowly added a solution of 6.6 grams (0.05 mole) of 2-thenyl cloride in 25 cc. of benzene. The mixture was heated at C. for one hour, treated with 15 cc. of water and 5 grams of 50% sodium hydroxide solution and stirred vigorously. The benzene-butanol layer was separated and fractionated. There was recovered 9.4 grams of unchanged N-phenyl-N',N'-dimethyl-ethylenediamine. A large amount of nonvolatile residue,- a quaternary salt. remained in the still. None of the desired tertiary amine was obtained.

When the procedure of Example III was repeated using considerably greater dilutions, for example, 4 to 5 times the amount of butanol, and a temperature of 25 C.. alarge amount of quaternary salt was obtained, and substantially only a trace of the desired tertiary amine was found.

Example IV To a solution of 19.2 grams (0.10 mole) of the free base, N-phenyl-N',N'-diethyl-ethylenediamine, in cc. of butanol at 25 0. there was added slowly a solution of 6.6 grams (0.05 mole) of 2-thenyl chloride in 65 cc. of benzene. The mixture was agitated at 25 C. for 19 hours, treated with water and excess alkali, and the benzene-butanol layer was separated and fractionated. There was obtained 9.0 grams unreacted N-phenyl-N',N diethyl-ethylenediamine and 9.0 grams of the tertiary amine, N-phenyl- N (2 thenyl) N',N diethyl ethylenediamine, boiling point 143145 C./11.5 mm.

The tertiary amine base, dissolved in a 3 to 1 mixture of carbon tetrachloride and acetone, was treated with dry hydrogen chloride gas. The dihydrochloride which precipitated was recrystallized with acetone containing a small amount of water. Melting point 144-146 C. (corrected).

This example illustrates the facility with which the tertiary amine is obtained when groups higher than methyl arepresent in the R3 and R4 positions of the secondary amine described hereinbefore.

Example V T a solution of 8.2 grams (0.05 mole) of the free base, N-phenyl-N',N-dimethyl-ethylenediamine, in 40 cc. of benzene there was added a solution of 3.2 grams (0.025 mole) of benzyl chloride in 10 cc. of benzene. The mixture Was refluxed for 20 minutes, when the reaction was sodium hydroxide solution, the quaternary salt separating as an oil insoluble in both the aqueous and benzene layers. On distillation of the benzene layer, only unchanged N-phenyl-N',N-dimethyl-ethylenediamine was recovered and none of the desired tertiary amine was obtained.

Example VI 2 To a solution of 9.5 grams (0.058 mole) of N-phenyl -N,N'-dimethyl-ethylenediamine in 5 cc. of 95% ethanol was added 3.1 grams (0.058

' mole) of ammonium chloride. The mixture was refluxed for one hour during which time ammonia was evolved. The mixture was cooled to 30 C. and a solution of 3.67 grams (0.029 mole) of benzyl chloride in cc. of ethanol was added I and the resulting mixture was heated at 65-70 C. for 8 hours. Thereafter, cc. of concentrated hydrochloric acid was added and the mixture was extracted with benzene to remove unreacted benzyl chloride. The mixture was treated with cc. of water, alkalinized with 50% sodium hydroxide solution and stirred vigorously at 55-60 C. The benzene layer was then separated and fractionated. There was recovered 5.3 grams of N-benzyl-N-phenyl-N',N-dimethylethylenediamine, boiling point 179-180 C./7 mm. The monohydrochloride was prepared by treating a benzene solution of the base with dry hydrogen chloride gas. The solid salt was filtered off, dried and recrystallized from ethanol. Melting point 210-211 C. (corrected).

Example VII The mono-acid phosphate of N-ethyl-N',N'- dimethyl ethylenediamine was prepared by adding 19.6 grams (0.1 mole) of phosphoric acid to a solution of 34.8 grams (0.3 mole) of N-ethyl- N ,N -dimethyl-ethylenediamine in approximately 100 cc. of butanol. To the resulting solution of the mono-acid phosphate was added a solutlon of 19.1 grams (0.15 mole) of benzyl chloride and the reaction mixture was heated at 65-70" C. for approximately 6 hours. Thereafter the reaction mixture was rendered alkaline with aqueous sodium hydroxide solution and the oily layer which separated was N-benzyl-N-ethyl- N,N'-dimethyl-ethylenediamine.

Example VIII The mono-acid sulfate of N-cyclohexyl-N,-N'-

dimethyl-ethylenediamine was prepared by adding 9.8 grams (0.1 mole) of sulfuric acid to a solution of 51 grams (0.3 mole) of N-cyclohexyl- N ',N'-dimethyl-ethylenediamine in approximate- 1y 100 cc. of acetone. To the resulting solution of the mono-acid sulfate was added a solution of 19.1 grams (0.15 mole) of benzyl chloride and.

the reaction mixture was heated at 40 C. for

approximately 8 hours. Thereafter, the reaction mixture was rendered alkaline with sodium hydroxide solution and the oil which separated was N benzyl N cyclohexyl-N,N-dimethy1-ethylcnediamlne. The disulphate salt of the free base tertiary amine was prepared by adding sulfuric acid to a solution of the free base tertiary amine in toluene.

This application is a division of our co-pending agplication, Serial No. 701,078, filed October 4, 1 46.

We claim:

1'. In the process of preparing a monobasic salt of a secondary amine of the formula:

in which R is a radical selected from the group consisting of aryl, alkyl, cycloalkyl, aryl-methyl and thienyl-methyl radicals, the steps which comprise heating a mixture of one equivalent of an ammonium salt of a mineral acid and a solution of approximately two equivalents of said secondary amine dissolved in an organic solvent containing a small amount of water until the evolution of ammonia ceases.

2. A process as defined in claim 1 in which the reaction is carried out at the reflux temperature of the mixture.

3. In the process of preparing a monobasic salt of N phenyl N',N-dimethyl-ethylenediamine, the steps which comprise heating a mixture of one equivalent of an ammonium salt of a mineral acid and a solution of approximately two equivalents of said diamine in an organic solvent containing a small amount of water until the evolution of ammonia ceases.

4. A process as defined in claim 3 in which the reaction is carried out at the reflux temperature of the mixture.

5. In the process of preparing a monohydrochloride salt of N-phenyl-N,N'-dimethyl-ethylenediamine, the steps which comprise heating a mixture of one equivalent of ammonium chloride with a solution of approximately two equivalents of said diamine in an organic solvent containing a small amount of water.

LUCAS P. KYRIDES. FERDINAND B. ZIENTY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,752,617 Schulemann et a1. Apr. 1, 1930 2,085,784 Bottoms July 6, 1937 2,418,237 Senkus Apr. 1, 1947 QTHER REFERENCES Moore et al., J. Chem. Soc. (London), vol. 101, pp. 1635-1676 (1912).

Fieser et al., Organic Chemistry, (D. C. Health and Co., Boston, 1944), pages 226-228.

Allott, Richters Organic Chemistry, (Elseview Publishing Co., Inc., 3rd ed., 1934), vol. 1, page 192. 

1. IN THE PROCESS OF PREPARING A MONOBASIC SALT OF A SECONDARY AMINE OF THE FORMULA: 